Now we calculate the edge current \(\mathbf {J}_{2\omega }\) . In the kinetic approach,
the response of an electron system to an external field is described by the Boltzmann equation for the electron distribution function \(f\) .
In our case \(f=f(\mathbf {p},x,t)\) , and the Boltzmann equation has the form [1]}, [2]}
\(\frac{\partial f}{\partial t} + v_x \frac{\partial f}{\partial x} + e \mathbf {\mathcal {E}} \cdot \frac{\partial f}{\partial \mathbf {p}} = \mathrm {St}f \:,\) 
